One proposed power output apparatus mounted on a vehicle includes an internal combustion engine, a planetary gear having a carrier and a ring gear respectively linked with an output shaft of the internal combustion engine and with an axle of the vehicle, a first motor outputting power to a sun gear of the planetary gear, and a second motor outputting power to the ring gear of the planetary gear (see, for example, Japanese Patent Laid-Open Gazette No. 2004-324424). The vehicle is further equipped with a catalytic conversion unit that uses a catalyst for catalytic conversion of an exhaust gas or emission from the internal combustion engine. In response to a deceleration request of the vehicle under the condition of a catalyst temperature of or over a preset reference level, this prior art power output apparatus prohibits fuel cutoff to the internal combustion engine to prevent deterioration of the catalyst. The power output apparatus continues explosive combustion of a fuel in the internal combustion engine, while controlling the first motor to generate electric power and lowering the rotation speed of the internal combustion engine. For continuation of the explosive combustion, a preset quantity of fuel, which slightly exceeds a minimum level ensuring no occurrence of a misfire, is to be continuously supplied to the internal combustion engine.